Question

Classify the following as amorphous or crystalline solids: Polyurethane, Naphthalene, Benzoic acid, Telfon, Potassium nitrate, Cellophane, Polyvinyl Chloride, Fiberglass, and Copper.

Answer 1

Hint: Solids are of two types: amorphous and crystalline, amorphous are those in which the geometry of the solid is irregular and when it is cut with a knife, clean surface is not obtained, and crystalline are those in which the geometry of the solid is regular and when it is cut with a knife, clean surface is obtained.

Complete step by step answer:
-Solids are those components in which the atoms and molecules are arranged very close to each other, the atoms and molecules don't have space for movement, so according to the arrangement of the atoms or molecules in the solid, solids are classified into two: amorphous and crystalline, amorphous are those in which the geometry of the solid is irregular and when it is cut with a knife, clean surface is not obtained, and crystalline are those in which the geometry of the solid is regular and when it is cut with a knife, clean surface is obtained.
-Crystalline solids are also known as true solids and amorphous solids are also known as pseudo solids or supercooled liquids.
So Polyurethane is an amorphous solid.
Naphthalene is a crystalline solid.
Benzoic acid is a crystalline solid.
Teflon is an amorphous solid.
Potassium nitrate is a crystalline solid.
Cellophane is an amorphous solid.
Polyvinyl chloride is an amorphous solid.
Fiberglass is an amorphous solid.
Copper is a crystalline solid.

Note: Crystalline solids are those solids that have a sharp melting point because they have definite heat of fusion and amorphous solids are those solids that do not have a sharp melting point because they do not have definite heat of fusion.